In the graphic on the left it can be seen the transmitted signal through our cavity in the frequency range 75-87 GHz. The peaks in the transmission correspond to resonances inside the cavity. The quality factor of most of these resonances is >1,000.

In the graphic on the right it can be seen the typical EPR spectrum obtained in a single-crystal of single-molecule magnets. In this case, it corresponds to a molecule wheel of spin S = 7.

Every absorption peaks corresponds to a transition between different projections of the spin of the molecule along the easy anisotropy axis.